1. Field of the Invention
The present invention relates to an air bag module and a method of folding an air bag in which the air bag is folded in a manner to deploy a series of stacked folded portions sequentially from a deep recess in a canister so that only filled portions of the air bag are allowed to interact with an occupant.
2. Background Art
It is well known that an air bag cushion is inflated with a gas when a vehicle encounters a sudden deceleration, such as in a collision. In such systems, the air bag cushion is typically housed in an uninflated and folded condition to minimize space requirements. In an emergency situation calling for deployment of the air bag cushion, inflation gas is released from an inflator to rapidly inflate and deploy the air bag cushion to interact with the vehicle occupant as the occupant moves forward within the vehicle passenger cabin. In general, such air bag cushions are designed to be inflated in less than one second.
Generally, it is desirable that an air bag cushion be stored in an out-of-the-way location until needed, and in such a manner that it can be rapidly activated to function in the desired manner. In modern vehicle designs, however, where space comes at a premium, out-of-the-way storage volumes for the storage of an air bag cushion are usually rather limited. Also, surface area is typically very limited on an instrument panel in which an air bag is stored.
It is desirable to provide a relatively large air bag and to deploy the air bag through a relatively small opening in the instrument panel to minimize usage of the fore/aft depth dimension of the air bag module as it relates to the surface area of the instrument panel from which the air bag is deployed.
Furthermore, in traditional air bag designs, the folded air bag is positioned on the deployment side of the inflator such that activation of the inflator pushes the folded air bag outward, and then the air bag fills. In this configuration, it is possible for an unfilled, folded portion of the air bag to interact with an occupant. However, it is desirable that only filled portions of the air bag be allowed to interact with the occupant.
Accordingly, it is desirable to provide an improved vehicle air bag module and method of folding an air bag that increases the potential for only filled portions of the air bag to advance toward an occupant during deployment, and in which the air bag deploys through a relatively small opening in the instrument panel from a deep recess in an air bag canister.
The present invention provides a new air bag folding concept in which packaging size of a passenger air bag module is reduced and in which the bag is folded in such a way that allows an orderly peeling away of each separate layer of the folded bag from a deep compartment of the air bag housing. By allowing the bag to peel out of the passenger air bag module housing, the potential for interaction of unfilled portions of the bag with an occupant is reduced.
More specifically, the invention provides an air bag module including an inflator having a deployment side through which gas is released in a deployment direction to fill an air bag. A canister includes a recess configured to receive the air bag in a folded condition. The recess has a deep bottom portion. The air bag includes an unfolded initial deployment portion positioned adjacent the deployment side, and a plurality of folded portions of the air bag stacked against the inflator in a direction perpendicular to the deployment direction and laying substantially flat and parallel to the deployment direction. At least one of the plurality of folded portions which are furthest from the inflator include perpendicularly bended portions which lie in the bottom portion of the canister. The folded portions are configured to deploy sequentially, starting with the folded portion nearest the inflator and ending with the folded portion furthest from the inflator, thereby helping to enable that unfilled portions of the air bag are only moved in the deployment direction as they fill with gas.
Preferably, the inflator has a deployment side, rear side, left side, and right side arranged generally in four quadrants about the periphery of the inflator. It is understood that the use of the terms xe2x80x9cleftxe2x80x9d and xe2x80x9crightxe2x80x9d herein are exemplary only, and such terms may be interposed, such as would be consistent with a corresponding description of a mirror image of the drawings described herein.
In one embodiment of the invention, the plurality of folded portions include three portions laying substantially flat and three portions having the perpendicularly bended portions. Also, the perpendicularly bended portions each have a distal end such that the distal ends are aligned in a manner substantially parallel with the deployment direction. The number of airbag folds may vary within the scope of the present invention based upon volume, shape and size of the airbag.
With this invention, no folded portions of the air bag are positioned toward the deployment direction from the inflator. Accordingly, only filled portions of the bag are advanced for interaction with the occupant.
Preferably, the bottom portion of the recess is located at an end of the recess which is opposite the deployment direction, such that the recess is relatively deep opposite the deployment direction and narrow perpendicular to the deployment direction to reduce surface space consumption on the surface of an instrument panel in which the air bag module is positioned.
Another aspect of the invention provides a method of folding an air bag for positioning within a recess of a canister having a bottom portion, with an inflator positioned for deploying the air bag. The inflator has a deployment side through which gas is expelled in a deployment direction to fill the air bag. The method includes the steps of: a) providing an unfolded initial deployment portion of the air bag in a configuration for attachment to the deployment side of the inflator; b) folding and stacking a plurality of folded portions of the air bag in a configuration parallel to each other, wherein those folded portions further from the initial deployment portion are longer in length than the folded portions which are nearer the initial deployment portion; c) bending the longer folded portions so that they each form a substantially right-angle configuration with a perpendicularly bended portion extending in a direction substantially perpendicular to the parallel configuration of the folded portions; and d) positioning the air bag in the recess in a manner such that the perpendicularly bended portions lie in the bottom portion of the recess.
The method may further include attaching the inflator to the initial deployment portion and positioning the stacked plurality of folded portions flat against a side of the inflator such that the parallel configuration of folded portions is parallel to the deployment direction of the inflator.
Accordingly, an object of the present invention is to provide an improved air bag module and method of folded an air bag which allows an orderly peeling away of each separate layer of the folded air bag from a deep bag compartment of the air bag module so that only filled portions of the air bag may interact with an occupant.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.